Brake control means



y 1938. B. s. AlKMAN 2,118,390

BRAKE CONTROL MEANS Filed July 28, 1936 2 Sheets-Sheet 1 73 H3 I24 I26 I 1 I4 1 [12 V15 H7 INVENTOR BUR TON S. AIKMAN ATTORNEY Patented ma 24, 1938 UNITED STATES PATENT QFFEQE BRAKE CONTROL MEANS Application July 28, 1936, Serial No. 92,965

22 Claims.

My invention relates to brake control systems and more particularly to such systems employing a plurality of braking means including a magnetic track shoe braking means.

One object of my invention is the provision of control means for magnetic track shoe brakes in which the track shoe windings are slightly energized before the shoes are brought into engagement with the track rail.

Another object of my invention is to control the degree of energization of the magnetic track shoe brakes in accordance with variations in straight air pipe pressure.

A further object of my invention is to so control the track shoe raising cylinder as to cause the track shoes to be lowered into engagement with the rail at the time the braking current is supplied to the shoe and to be raised from engagement with the rail at the time the energizing circuit for the track shoe is interrupted.

Another object of my invention is the provision of means for automatically interrupting the energization of the magnetic track shoe when the vehicle comes to rest or the rate of retardation of the vehicle decreases to a predetermined low value, to prevent the windings thereof from burning out or becoming overheated.

A further object of my invention is the provision of means responsive to the rate of retardation of the vehicle for controlling the application and release of the magnetic track shoe braking means after the brake controller device is moved to its brake applying position.

A still further object of my invention is the provision of means responsive to movement of the brake controller device to a brake applying position for effecting the initial application of the track shoe braking means independently of the rate of retardation of the vehicle.

Other objects and advantages of my invention will appear from the following description, reference being had to the accompanying drawings in which Figs. 1 and 2, taken together, are a diagrammatic view of apparatus and circuits comprising one preferred embodiment of the invention,

Fig. 3 is a plan view of the brake valve device shown in Fig. 1, and

Fig. 4 is a sectional view taken on the line 4-4 in Fig. 1.

Referring to the drawings, my invention contemplates the use of a fluid pressure braking means comprising a brake cylinder I that is supplied with fluid under pressure from the main reservoir 2 through main reservoir pipe 3, as

controlled by the brake valve device 4, through straight air pipe 5, the automatic valve device 6 and brake cylinder l. A magnetic track braking means is also provided comprising the track shoe 8 that is controlled by the resistor 5 device 9 and the contactor 12 in cccrdance with the pressure in the brake cylinder pipe T as controlled by the brake valve device i. The magnetic track brake is controlled by the resistor unit device Q in accordance with the pressure in the brake cylinder pipe 1, by a contactor l2 and an inertia controlled pilot switch device 13 that is carried on the brake valve device 4.

The brake valve device 4 comprises a casing having a main body portion 54, a seli-lapping valve portion 55 and a base or bracket portion IS, the three portions together defining a pres-- sure chamber i! that is in open communication with the brake cylinder through straight air passage and pipe E8, the automatic valve device 6 and brake cylinder pipe I.

The self-lapping valve portion i5 is provided with a supply valve chamber l9 to which a feed valve device 22 of the usual type supplies fluid under pressure at a reduced pressure from the main reservoir 2 through the main reservoir pipe and passage 3. A supply valve 23 is provided in the valve chamber l9 and is slidably disposed within a bore 24 in the casing to engage a seat 25 provided in the valve portion of the casing. The supply valve 23 is subject to the pressure of a spring 26, one end of which engages the valve and the other end of which engages a nut 21 screw-threadedly attached within a bore in the valve portion of the casing.

The self-lapping valve portion or section of the casing I4 is also provided with a cylinder 28 which is open at one end to the pressure chamber H, the other end of the cylinder being closed by an adjusting member 29 screw-threadedly attached Within a bore in the self-lapping valve casing portion. The adjusting member 25 is provided with a central bore 32 which, at its outer end, is adapted to receive a screw 33 for attach ing a cap member 34.

Operatively mounted in the cylinder 28, adjacent its open end, is a movable abutment in the form of a piston 36 having a stem 31 which is slidably guided by the adjusting member 29 within the inner end of a bore 32. At one end of the piston 36 is a chamber 38 which is constantly open to the atmosphere through an exhaust passage and port 39. A coil spring M is contained in the chamber 38 and is interposed between and engages the inner face of the piston 36 and the inner face of the adjusting member 29.

A release valve chamber E2 is provided within the piston that is in open communication with the pressure chamber li through a passage 33. A release valve M is contained within the Valve chamber i2 and is adapted to seat on the valve seat formed on the piston and which is operative to control communication between the valve chamber i2 and the chamber 38 through connecting passages The release valve is provided with a stem ii, the small end of which slides within a bore in the stem of the piston 36 and the larger end of which is provided with a collar 38 which slidably engages the piston within a central bore 29 and is subject to the pressure of the release valve spring 52 interposed between the engaging collar 48 and the annular flange 53 on the piston. Outward. movement of the release valve relative to the piston 3 is limited by the collar lil which engages a stop flange 5 5 that is secured to the piston 33.

A mechanism is provided for controlling the operation of the supply valve 23 and the release Valve 42 comprising spaced levers 55, that are pivotally mounted intermediate their ends on a pin 56, supported in a plunger al that is slidably guided within a bore 58 in the casing of the selflapping valve portion it.

The lower end of the spaced levers 55 are connected together by a pin 5Q which is loosely mounted within a roller 62 that is adapted to operatively engage the outer end of the release valve stem 37. The upper end of the spaced levers 55 are connected together by a pin 63 to which one end of the operating rod '6 is pivotally mounted, the opposite end of the rod 65 operatively engaging the supply valve 23 within a recess 65 formed in its face. For the purpose of operating the plunger 5i toward the right is provided an operating cam 6K5 mounted upon a shaft 161 that is carried in an upper bearing 6% and in a lower bearing 69, and is arranged to be operated by the brake valve handle '52. As the handle 712 is moved progressively from its release position toward full service position the cam 55 forces the plunger 5'! progressively toward the right.

It will be appreciated that the force of the release valve spring 52 is less than the force of the supply valve spring 26, which is less than the force of the regulating spring l l. When the cam 56 and the plunger 5'? are in their release positions, as shown in Fig. l, the spring 25 forces the supply valve 23 toward the left to its seated position and the spring 52 forces the release valve M toward the left to its unseated position.

The inertia controlled pilot switch device it is mounted on a bracket :73 supported from the body portion M of the brake valve device and com prises fixed contact members it and it that are adapted to be engaged by a movable contact member '66 that is carried by a lever 'll mounted on a pin '58 that is attached to the bracket iii. A spring .79 is provided for urging the lever ii and the switch contact member "i5 downwardly to normally maintain the contact member '53 out of engagement with the contact members "i i and 75. An inertia pendulum 32 is provided that is mounted on a hub 83 extending from the bracket '53, the ball bearings 3d providing easy movement of the pendulum in accordance with the rate of retardation of the vehicle to present a cam face 55 against a roller 36 that is mounted on a pivot pin 8i carried by the lever ll. A raised portion 88 is provided for raising the roller the lever l7 and the switch contact member l6 upon movement of the pendulum 32 toward the left from its vertical or illustrated position.

A time limiting mechanism is provided for urging the pendulum 8'2 toward the left for a short interval of time upon movement of the brake valve handle 52 to a brake applying position. This mechanism includes a movable piston 89 positioned within a bore 92 provided in the bracket casing and having a stem 93 extending through an opening A l in one end of the casing and adapted to engage the pendulum 82. The piston 89 divides the bore 92 into a chamber 95 that is in constant communication with a chamber 9% through port ill, and a chamber 93 that is in constant communication with the atmosphere through port 99. A spring liil is provided within the chamber 98, one end of which engages the outer end of the bore and the other end of which engages one side of the piston to force the piston toward the right until the stop member Hi3 thereon engages the opposite end of the bore.

A vertical bore EM is provided in the casing above the bore 92, containing a piston Hi5 dividing the bore into the aforenamed chamber 96 and a chamber we that is in communication with the atmosphere through port lili. A spring W8 is provided within the chamber the lower end of which en ages a partition in the casing and the upper end of which engages the piston N35 to force it upwardly against a stop Hi9 extending downwardly from the upper casing wall. The piston i535 is provided with a stern H2 extending upwardly through an opening in the upper casing wall and adapted to engage a lever H3 that is pivotally mounted on a pin lid on the bracket '53 in the opposite end of which is an opening M5.

A piston chamber M6 is also provided in the bracket casing that is in constant communication with a safety control pipe ill and which contains a piston H8 having a stem lifil extending upwardly therefrom through an opening the upper casing wall and having a reduced portion that extends through the opening 2 in the lever H3, and provided with a head on the upper end thereof for a purpose to be later explained. A spring l23 is provided about the stem M9, the upper end of which engages the casing wall and the lower end of which engages the piston l 58 for urging the piston 2 l8 and the stem H9 downwardly upon the release of fluid under pressure from the piston 5 iii. The lever H3 is provided with a fiat portion i2 1- that is so positioned as to be adapted to be engaged by a cam surface E25 on the under side of a seg ment I26 mounted on the shaft 5i and rotatable therewith upon movement of the brake valve handle '52.

The automatic valve device 5 comprises a oasing providing a piston chamber iii? containing a piston I28 having a stem i223, extending into a valve chamber ifil on the opposite side of the piston that is in constant commun cation with a main reservoir pipe w: 1 contains a slide valve E32 operatively connected to the stem 529. A spring provided within the piston chamber 2? for norn ally urging the piston E28 and the slide valve liifi to their illustrated positions in which a cavity M 2 in the slide valve [32 effects communication between the straight air pipe 5 the brake cylinder pipe l.

A foot valve device 535 is provided having a casing providing a valve chamber lfit that is in constant communication with a main reservoir pipe 3, a chamber I31 that is in constant communciation with the safety control pipe I I1 and a chamber I38 that is in constant communication with the atmosphere through exhaust port I39. A diaphragm valve I42 is provided within the chamber I38 and is adapted to be forced by a follower I43 against its rib seat I44 to close communication from the safety control pipe and chamber I31 to the atmosphere through chamber I38 and exhaust port I39. A foot lever I45 is provided pivotally connected to the casing by a pin I46 and urged in a counterclockwise direc tion by a. spring I41 one end of which engages the lever I45 and the other end of which engages the casing of the foot valve device. A valve I48 is provided within the chamber I36 and is provided with a stem I49 extending through the chamber I31 into engagement with the diaphragm valve I 42, the valve I42 acting against the stem I49 to force the valve I48 from its seat against the bias of a spring I5I provided within the chamber I36 when the valve I42 is in its. seated position. Upon the release of pressure from the lever I45, the spring I41 urges the lever upwardly, thus relieving pressure against the follower I43 and permitting the spring I5I to force the valve I43 to its seat to close communication between the main reservoir pipe 3 and the safety control pipe I I1, the stem I49 acting at the same time to force the diaphragm valve I42 from its seat to effect communication between the safety control pipe H1 and the atmosphere through chambers I31 and I38.

The resistor device 9 comprises a tubular casing I52 having a lining I53 of insulating material therein containing a stack of Wafers I54 of conducting material, such as carbon, connected between the fixed terminal I55 at the right hand end and a movable pressure terminal I56, carried by a lever I51 that is pivotally mounted on a pin I58 carried at one end of a rod I59 extending through an opening in a bracket I62 that extends upwardly from the casing I53. A spring I 63 is provided about the rod I59, one end of which engages the bracket I62 and the other-end of which engages a collar I64 carried on the rod I59 for urging the rod and pivot pin I58 toward the right to their illustrated positions, so long as the pressure on the spring I63 is below a predetermined value. A contact member I65 that is electrically connected to the terminal I56 is carried by the resilient support I66 and is adapted to engage the fixed contact member I61 that is connected by conductor I68 to the terminal I55 for a purpose to be later explained.

On the under side of the casing I52 a pressure operated switch is provided comprising fixed contact members I12 and I13 that are carried by a supporting bracket I14 and insulated from the casing structure, and a movable contact member I 15 that is carried by a stem I16, the smaller end of which is guided within a bore in the bracket I14 and the larger end of which is guided within a bore in a stem I11 that is carried in a bore I18 within the casing structure and terminates in a diaphragm follower I19 that engages one side of the diaphragm I82 on the opposite side of which is provided a diaphragm chamber I83 that is in constant communication with a brake cylinder pipe 1. A spring I84 is provided about the rod I16, one end of which engages a collar I85 on the end of the stem I11 and the other end of which engages the support I86 carrying the movable contact member I15 to provide a resilient connection between the contact member I15 and the stem I11 upon movement thereof to a switch closing position. A spring I81 is provided within the bore I18, the right hand end of which engages a nut I88 that is screw-threadedly attached within the end of the bore I18, and the other end of which engages in. an enlarged portion of the stem I11 to urge the stem. toward the left. A portion of the stem is reduced to form shoulders I92 and I93 to engage opposite sides of the bifurcated end I 94 of the lever I51 for actuating the lever and the pressure terminal I56 upon movement of the same. A resistor I95 is permanently connected between the switch terminal I13 and the common power terminal I55.

The contactor device I2 comprises a magnetic core consisting of the fixed portion I96 and a movable armature portion I98 pivotally connected thereto by a pin I99, and adapted to be actuated thereby upon the energization of a winding I91, to cause engagement of the movable contact member 204 with a fixed contact member 203. A spring 202 normally urges the armature member and the contact member 204 toward their illustrated positions. The core portion I96 is mounted upon a casing providing a valve chamber 205 containing a valve 206 that is urged toward its seat by a spring 201 therein to close communication between the chamber 205 and a chamber 208 that is in constant communication with a pipe 209 and a piston chamber 2 of the track shoe device 8. An exhaust valve chamber is also provided that is in constant communication with the atmosphere through exhaust port 2I2 and which contains a valve 2I3 having a valve stem 2I4 provided with collars 2I5 for engaging the opposite sides of the bifurcated lower end 2I6 of the armature. I98. The valve 206 is provided with a stem 2 I 1 for engaging the valve 2 I3. In the deenergized condition of the contactor I2 the spring 202 urges the armature I98 to its illustrated position, the lower end 2I6 thereof biasing the valve 2I3 to its seat and the valve 206 from its seat against the bias of the spring 201, thus eifecting communication from the main reservoir pipe 3 to the piston chamber 2 of the track shoe device 8.

The track shoe device 8 comprises a track shoe 2! for engaging the track rail 2I9 and is normally held suspended above the track rail by the supporting bracket 22I, the piston stem 222 and the piston 223 in the aforementioned piston chamber 2 provided in a casing 224 carried on the car or truck structure.

Charging the system The system is charged by the flow of fluid under pressure from the main reservoir 2 as supplied by the feed valve device 22 at a reduced pressure to the main reservoir pipe 3, to charge the supply valve chamber I9 on the brake valve device 4. Fluid under pressure also flows from the main reservoir pipe 3 through chambers 205 and 208 of the contactor device I2, pipe 209, to the. piston chamber 2| I of the track shoe raising cylinder 224, thus forcing the piston 223 and the track shoe 2I8 upwardly to disengage the track shoe from the rail.

To charge the system it is necessary that the operator maintain pressure on the foot lever I45 urging the lever downwardly against the bias of the spring I41 to its illustrated position, thus forcing the diaphragm valve I42 against its rib seat I44 to close communication between the safety control pipe H1 and the. atmosphere and to unseat the valve I48 to effect communication between the main reservoir pipe 3 and the safety control pipe ill. Fluid under pressure thus flows from the main reservoir pipe 3 to the safety control pipe I I1 and to the piston chamber I27 of the automatic valve device 6, the combined pressure within the piston chamber I2! and the force of the spring I33 forces the piston I28 and the slide valve I32 to the right or to their illustrated positions. Fluid under pressure also flows from the safety control pipe ill to the piston chamber H6 of a time limiting control mechanism for controlling the inertia pilot switch, thus forcing the piston H8 upwardly against the bias of the spring I23 thus reducing pressure on the upper side of the lever H3 and permitting the spring 108 to force the piston I05, the stem H2 and the lever H3 upwardly to their illustrated positions. Fluid under pressure also flows from the main reservoir pipe 3 to charge the slide valve chamber l3| of the automatic valve device 6.

Service application of the brakes If the operator wishes to a service application of the brakes the. handle '42 of the brake valve device t is moved from its release position an amount depending upon the desired degree of application of the brakes. Upon the initial movement of the handle from its release position the sloping surface of the cam 66 moves against the plunger 51, forcing the plunger toward the right. The first part of this movement effects a compression of the release valve spring 52 and forces the release Valve 4 3 to its seat, closing communication between the pressure chamber l? and the atmosphere through passages 33, iii and Further movement of the plunger 5'? toward the right causes the spaced levers 55 to pivot about their lower end, further movement of the roller e2 being prevented by the stiffness of th regulating spring 4|, thus causing the rod 5 to force the supply valve 23 against the compression of the supply valve spring 26 to open communication between the main reservoir pipe 3 and the pressure cham-- her i! through the supply valve chamber is, thus supplying fluid under pressure from the main reservoir 2 to the pressure chamber l? and to the brake cylinder l through straight air pipe 53, the cavity I34 in the slide valve. 532 of the automatic valve device 6 in its illustrated position, and brake cylinder pipe l. The pressure established in the pressure chamber ii, and in the brake cylinder l, is dependent upon the degree. of movement of the operating lever '32 and of the plunger 5'5 from their release positions, since, when the pressure within the chamber ii is increased due to the flow of fluid thereto through the. supply valve chamber ii! a like pressure is exerted on the chamber side of the piston 36 in opposition to the pressure exerted by the regulating spring M. This pressure continues to build up until it becomes sufficient to force the piston 36 toward the right, thus relieving the pressure on the roller 62 and permitting the supply valve spring 25 to force a rod 64 toward the left, pivoting the lever 55 about the pivot 55 and moving the supply valve '23 into engagement with its seat 25.

The amount of pressure on the chamber side of the piston 36 necessary to eifect sufficient movement of the piston 36 to cause a supply valve 21% to seat is dependent upon the amount of movement of the operating lever J2 and of the plunger 5? from their release positions. The greater the movement of the operating lever 'ifl from its release position the greater will be the amount of movement of the pivot pin 56 toward the right,

and, consequently, the greater will be. the com-- pression of the regulating spring 4! necessary to permit movement of the lever 55 and of the rod 6% to effect the seating of the supply valve 22%. It will be apparent therefore, that the brake valve device is self-lapping on a pressure basis, the degree of fluid pressure within the pressure chamber I! necessary to effect the movement of the valve to lap position being dependent upon the degree of movement of the operating lever 52 from its release position.

As the lever E2 of the brake valve device t is moved to any position within the pneumatic service zone the surface I25 of the segment lZG engages the surface I24 on the lever H3, thus causing the lever to move in a clockwise direction about the pin H4 and to force the stem H2 and the piston 55 downwardly against the bias of the spring H38. Fluid under pressure in the chamber 96 is thus forced through the port 97 into the piston chamber to force the. piston 39 and the stem 93 toward the left, the end of the stem 93 engaging the pendulum 82 and forcing it to move in a clockwise direction about the central hub thus causing the raised surface of the cam acting against the roller 86 to move the lever ii in a counterclockwise direction and cause engagement of the switch contact member '16 with the con tact members E and 75. A tickler or magnetizing circuit is thus completed from the over-head line conductor 232 through trolley 233, conductor 234, the switch contact members l4, l5 and iii, and conductor 235, to the terminal N3 of the pressure operated switch on the resistor device 9 through resistor lSE, conductor and the winding of the track shoe 2 lit, to ground at 231. Ihe resistor 895 is so designed as to permit the supply of magnetizing current only to the brake shoe 2 I 8, and is insufficient to cause an appreciable braking action.

As the pressure in the brake cylinder pipe "I and in the diaphragm chamber 33 of the pressure operated switch builds up to a predetermined low value, the follower H9 and the stem if! are moved toward the right to cause engagement of the switch contact member H5 with the contact members H12 and ll l to close a circuit from the over-head line conductor 232, as above traced, to the. terminal of the contact member i2 3, through switch contact members H3, H5, and H2 conductor 23? through the winding IQ! of the contactor l2, and conductor 238 to ground at 239, thus causing movement of the armature Hit in a counterclockwise direction about the pivot pin Hill to effect engagement of the contact member 2134 with contact member 283 and movement of the bifurcated lower end of the. armature 2th toward the right, thus permitting the valve 286 to be moved to the right to its seat and the valve 2E3 to be moved to the right from its seat to close communication as above described between the main reservoir pipe 3 and the piston chamber 2! l of the track shoe raising cylinder 224 and to per mit the release of fluid under pressure from the piston chamber 2H through pipe 269 and eX- haust port 2 l2.

Engagement of the contact members 204 and 293 completes a braking circuit from the overhead line conductor 232, through trolley contact members 203 and 2M, conductor 2 32, to the terminal I56 of the stack of carbon pile wafers E54, through the carbon pile stack to the terminal 555, the conductor 23%, the winding of the. track shoe magnet and to ground at 231. It will be noted that a portion of the above traced circuit through ,the.

the carbon pile resistor I54 is in parallel circuit relation with the said portion of the circuit through the resistor !05. As the pressure in the brake cylinder I and in brake cylinder pipe T and diaphragm chamber I83 builds up, the stem I7? is urged further toward the right against the bias of the spring 181, thus moving the lever I5 v further in a counterclockwise direction about the pivot pin I58 to bring a greater pressure on the carbon pile stack I5 5, and thus to decrease resistance of the carbon pile stack to thereby increase the current flow through the winding of the track shoe 2I8 to provide a braking ou cut that is substantially proportional to brake pressure. If the pressure in the brake cylinaer and in the diaphragm chamber I83 builds up to a sufiiciently high value, thus creating a sufiiciently high pressure of the terminal member 55% on the carbon pile stack, the force of the 563 will no longer be sufiicient to maintain the rod is and the pivot pin I 58 in their illustrl ed tions, and the lever I51 will move in a col :itcr clockwise direction about the terminal I56 a fulcrum, causing the contact member 5 55 to engage the contact member I51 and close a circuit in shunt relation to the carbon pile stack i5 1, through contact members I05, I51, conductor I03, to theterminal I55, thus effecting maximum energization of the track brake shoe.

The initial movement of the pendulum 82 toward the left, caused by movement of the piston 89 and the stem 93, is of short time duration due to the leakage of fluid under pressure past the piston 89, this being so arranged that after a short time interval the pendulum 82 will no longer be prevented by the stem 93 again resuming its illustrated position.

The retardation of the vehicle causes the pendulum 02 to be moved in a clockwise direction, a predetermined minimum rate of retardation being required to cause the roller 86 to ride upon the cam surface 88 sufiiciently to maintain the switch contact member I6 in engagement with the switch contact members I4 and I5, as above described, to permit the energization of the track shoe brake. So long as the rate of retardation of the vehicle is suflicient to maintain the switch contact member I6 in its circuit closing position, and so long as the pressure in the brake cylinder is sufficient to maintain the pressure operated switch contact member I15 in its circuit closing position, the winding of the track shoe 2! will remain energized. However, upon a decrease in the rate of retardation of the vehicle below the predetermined minimum rate, or upon the com-- plete stopping of the vehicle the pendulum 82 will move to substantially its illustrated position, permitting the switch contact member IE to move out of engagement with the contact members I4 and I5. Upon the disengagement of contact member I6 from contact members I4 and I5, the contactor I2 is shifted to open the braking circuit through the winding of the track shoe 2 I8 and cause re-supply of fluid under pressure through pipe 209 to the piston chamber 2II of the track shoe raising cylinder 224 to raise the track shoe out of contact with the rail 2I9, the track shoe brake being thus released.

It will be evident, and it is so intended, that with the energizing circuit for winding 19! of contactor I2 through the inertia controlled pilot switch I3 interrupted, the current supplied to the contactor winding I9I from the overhead conductor 232 by way of contact members 203 and 204 of contactor I2, wire 242, resistor 9 or parallei-connected resistor 9 and shunt I68, resistor 95, contact members I13, I86, "2 of the brake cylinder pressure responsive switch, and wire 23! is insufiicient to hold the contact members 203 and 204 of the contactor I2 in engagement against the tension of the spring 202 of the contactor.

t will thus be seen that the pressure in the brake cylinder pipe I controls both the degree of application of the fluid pressure brakes and the degree of application of the track brake to effect a corresponding increase and decrease in the degree of application of the two brakes, and, that upon the stopping of the vehicle the electric track brake will be deenergized irrespective of whether the lever I2 is moved to release position to release the fluid pressure brakes.

If the operator wishes to release the brakes, the handle I2 is moved to release position, thus moving the cam 66 out of engagement with the plunger 51 and permitting the release valve spring 52 acting against the release valve stem 41 to force the roller 62 and the spaced levers 55 toward the left to unseat the release valve 42 and permit the flow of fluid under pressure from the pressure chamber I! and the brake cylinder I to the atmosphere through passages 43, 45 and 39.

If the brakes are released while the vehicle is in motion and the switch contact member I6 is in engagement with the switch contact members I4 and I5, the winding of the track shoe 2H3 will remain energized until the brake cylinder pressure has reduced sufliciently to permit movement of the diaphragm I82 by the spring IE! to move the switch contact member II5 out of engagement with the switch contact members I I2 and I13, to deenergize the winding I9! of the contactor I2, and permit movement of the armature :98 thereof to its illustrated position by the spring 202. Movement of the armature I 98 to cause separation of the contact member 204 from the contact member 203 interrupts the circuit through the winding of the track shoe 2I8, and, at the same time, causes movement of the valve 2I3 to its seat to close communication between the piston chamber 2 of the track shoe raising piston 224 and the atmosphere through the exhaust port 2I2 of the contactor device I2, and causes movement of the valve 206 from its seat to effect the supply of fluid under pressure from the main reservoir pipe 3 through pipe 209 to the piston chamber 2! I to raise the track shoe 2I8 from engagement with the track rail. It will be noted that the operation of thecontactor device I2 controls both the energizing circuit to the track shoe and the supply of fluid under pressure to the piston chamber 2 I I of the track shoe raising cylinder to effect the lowering of the track shoe into engagement with the track rail at the time the track shoe is energized to effect the raising of the track shoe from engagement with the rail at the time the track shoe is deenergized.

Emergency application Fig. 3)

on the lever i lli oi the foot valve device H35, to release fluid under pressure from the piston chamber 52? of the automatic valve device and from the safety control pipe ili. Upon relieving pressure from the lever M5 of the root valve device the spring i al forces the lever in a countenclockwise direction, thus permitting the spring l5i to force the valve 12 to its seat to close communication between the main reservoir pipe 3 and the safety control pipe it and to force the diaphragm valve i i-2 from its rib seat to effect communication between the safety control pipe li'i and the atmosphere through chambers i32 litand the exhaust port E39. Upon the release of fluid under pressure from the piston chamber it? of the automatic valve device 5 the piston LZS and the slide valve I32 are moved toward the left against the bias of the spring l32 by the greater pressure within the slide valve chamber liii to effect communication between the main reservoir pipe 3 and the brake cylinder l through slide valve chamber iil, past the right hand end of the slide valve E32.

The release of fluid under pressure from the safety control pipe iii also effects a reduction in pressure in the piston chamber lid of the time limiting control mechanism cciated with the inertia controlled pilot switch it, thus permitting the spring i23 to force the stem i it and the piston H8 downwardly. Upon downward movement of the stem Me the head i272 actuates the lever H3 in a counterclockwise direction about the pivot pin UM, thus forcing the stem H2 and the piston m5 downwardly against the bias of the spring 8E8 to force fluid under pressure from the piston chamber into the piston chamber t5 and force the piston 39 and the stem 93 toward the left. The force of the stem 93 against the pendulum s2 causes it to move in a clockwise direction about the hub 83, the cam surface 88 engaging the roller 8% and causing the lever H to be moved in a counterclockwise direction to effect engagement of the switch contact member '56 with the switch contact members M and iii to close the above traced tickler circuit through the resistor i235 and the winding of the track shoe M8. Upon the increase in brake cylinder pressure the pressure operated switch contact member H5 is forced into engagement with the switch contact members and lid to operate the contactor E2 to its circuit closing position in the manner above described for service application of the brakes. The carbon pile stack is compressed to increase the energization of the winding of the track shoe 258 in correspondence with the increase in brake cylinder pressure.

While one preferred embodiment of my invention has been illustrated. and described, it will be apparent to those skilled in the art that many modifications and changes in the apparatus and circuits illustrated may be made within the spirit of my invention, and I do not wish to be limited otherwise than by the scope of the appended claims.

Having now described nly invention, what I claim as new and desire to secure by Letters Patent, is:

1. In a brake equipment for vehicles, in combination, a brake cyiinder, magnetic track shoe braking means for engaging the track rail, an electric circuit for energizing track shoe braking means, manually operable means for applying the brakes, and inertia responsive means responsive to the rate of retardation of the vehicle when the manually operable means is in a brake applying position for maintaining the energizing circuit of said track shoe closed and for interrupting said circuit when the vehicle comes to rest.

2. In a brake equipment for vehicles, in combination, a brake cylinder, magnetic track shoe braking means adapted for engagement with the track rail, manually operable means for eiTecting the supply of fluid under pressure to said brake cylinder, and means for effecting the energization of said track shoe comprising means responsive to the brake cylinder pressure and inertia means responsive to the rate of retardation of the vehicle, said inertia means being ef fective to interrupt the track shoe circuit when the vehicle comes to rest.

3. In a brake equipment for vehicles, in combination, a brake cylinder, magnetic track shoe braking means adapted for engagement with the track rail, an electric circuit for energizing said track shoe braking means, manually operable means for eiiecting the supply of fluid under pressure to the brake cylinder, means responsive to movement of said manually operable means to a brake applying position for initially energizing said track shoe braking means, and inertia responsive means responsive to the rate of retardation of the vehicle when the manually operable means is in a brake applying position for maintaining the energizing circuit for the mag netic track shoe, and for interrupting said circuit when the vehicle comes to rest.

4. In a brake equipment for vehicles, in combination, a brake cylinder, magnetic tracl: shoe braldng means adapted for engagement with the track rail, an electric circuit for energizing said track shoe braking means, manually operable means for effecting the supply of fluid under pressure to said brake cylinder, inertia means responsive to the rate of retardation of the vehicle when the manually operable means is in a brake applying position for maintaining said track shoe energizing circuit closed and for interrupting said circuit when the vehicle comes to rest, and a dash pot mechanism responsive to movement of said manually operable means to a brake applying position for initially actuating said inertia means to efiect an initial slight energization of said track shoe braking means.

5. In a brake equipment for vehicles, in combination, a brake cylinder, magnetic track shoe braking means adapted for engagement with the track rail, an electric circuit for energizing said track shoe braking means, manually operable means for effecting the supply of fluid under pressure to the brake cylinder, means for closing said electric circuit comprising a contactor responsive to brake cylinder pressure and an inertia switch responsive to the rate of retardation of the vehicle, and means responsive to movement of said manually operable means to a brake applying position for actuating said inertia switch to its circuit closing position and for maintaining it in that position for a short interval of time.

6. In a brake equipment for vehicles in combi nation, a brake cylinder, magnetic track shoe braking means adapted for engagement with the track rail, an electric circuit for energizing said track shoe braking means, manually operable means for effecting the supply of fluid. under pressure to said brake cylinder, a contactor device for controlling said electric circuit, and means for controlling said contactor device comprising a pressure operated switch responsive to brake cylinder pressure and an inertia switch responsive to the rate of retardation of the vehicle.

'7. In a brake equipment for vehicles, in combination, a brake cylinder, magnetic track shoe braking means adapted for engagement with the track rail, an electric circuit for energizing said track shoe, manually operable means for effecting the supply of fluid under pressure to said brake cylinder, a contactor device for controlling said electric circuit, means for controlling said contactor device comprising a pressure operated switch responsive to brake cylinder pressure and an inertia switch responsive to the rate of retardation of the vehicle, and means for lowering said track shoe into engagement with the track rail upon operation of said contactor device to effect the supply of a braking current to said track shoe and for raising said track shoe from engagement with the track rail upon operation of said contactor device to interrupt the braking current through said track shoe.

8. In a brake equipment for vehicles, in combi nation, a brake cylinder, magnetic track shoe braking means adapted for engagement with the track rail, an electric circuit for energizing said track shoe braking means, manually operable means for effecting the supply of fluid under pressure to said brake cylinder, inertia switch means responsive to the rate of retardation of the vehicle for closing a tickler circuit for magnetizing the magnetic track shoe, and means including said inertia switch means for closing a braking circuit for said track shoe braking means upon movement of said manually operable means to a brake applying position, said inertia switch means being effective to interrupt the braking circuit for said magnetic track shoe braking means when the vehicle comes to rest.

9. In a brake equipment for vehicles, in combination, a brake cylinder, magnetic track shoe braking means adapted for engagement with the track rails, manually operable means for effecting the supply of fluid under pressure to said brake cylinder and for establishing a magnetizing circuit for said track shoe, and means responsive to brake cylinder pressure for establishing a braking circuit for said track shoe.

10. In a brake equipment for vehicles, in com bination, a brake cylinder, magnetic track shoe braking means adapted for engagement with the track rail, manually operable means for effecting the supply of fluid under pressure to said brake cylinder and. for initially effecting the supply of magnetizing current to said track shoe, and means responsive to a predetermined brake cylinder pressure for effecting the supply of a braking current to said track shoe and for thereafter increasing said braking current in accordance with the increase in brake cylinder pressure.

11. In a brake equipment for vehicles, in combination, a brake cylinder, magnetic track shoe braking means adapted for engagement with the track rail, a tickler circuit for supplying magnetizing current to said track shoe, a braking circuit for supplying braking current to said track shoe, manually operable means for effecting the supply of fluid under pressure to said brake cylinder and for initially closing said tickler circuit, means responsive to brake cylinder pressure while said manually operable means is in a brake applying position for effecting, simultaneously, the closing of said braking circuit and the lowering of said track shoe into engagement with the track rail and for effecting, simultaneously, the interruption of said braking circuit and the raising of said track shoe from the rail.

12. In a brake equipment for vehicles, in combination, a brake cylinder, magnetic track shoe braking means adapted for engagement with the track rails, an electric braking circuit for energizing said track shoe, manually operable means for effecting the supply of fluid under pressure to said brake cylinder, and means responsive to brake cylinder pressure for effecting, simultaneously, the closing of said braking circuit and the lowering of said track shoe braking means into contact with the track rail upon an increase in brake cylinder pressure to a predetermined value and for effecting the interruption of said braking circuit and the raising of said track shoe braking means from engagement with the track rail upon the lowering of the brake cylinder pressure to a predetermined minimum value.

13. In a brake equipment for vehicles, in combination, a brake cylinder, magnetic track shoe braking means adapted for engagement with the track rail, an electric circuit for eifecting the supply of a magnetizing current only to said track shoe braking means and an electric braking circuit for controlling the supply of braking current to said track shoe braking means, manually operable means for effecting the supply of fluid under pressure to said brake cylinder, pressure responsive means subject to a predetermined low brake cylinder pressure for closing said braking circuit, and a rheostat in said braking circuit effective upon an increase in brake cylinder pres sure above said predetermined low value for controlling said braking current for increasing the track shoe braking effort in accordance with the increase in oral-2e cylinder pressure.

14. In a brake equipment for vehicles, in combination, a brake cylinder, magnetic track shoe braking means adapted for engagement with the track rail, an electric circuit for energizing said track shoe braking means, manually operable means for effecting the supply of fluid under pressure to said brake cylinder, switching means for effecting the energization of said track shoe braking means comprising inertia responsive switching means responsive to the rate of retardation of the vehicle and pressure responsive switching means subject to brake cylinder pressure.

15. In a brake equipment for vehicles, in combination, a brake cylinder, magnetic track shoe braking means for engagement with the track rail, manually operable means for effecting the supply of fluid under pressure to said brake cylinder, means for establishing a magnetizing circuit for said track shoe braking means comprising an inertia responsive switch responsive to a predetermined rate of retardation of the vehicle, means for establishing a braking circuit for said track shoe braking means comprising said inertia responsive switch and switch mechanism responsive to a predetermined low value of brake cylinder pressure, and means responsive to an increasing value in brake cylinder pressure for inreasing the braking current to said track shoe braking means.

16. In a brake equipment for vehicles, in combination, a brake cylinder, magnetic track shoe braking means for engagement with the track rail, manually operable means for eifecting the supply of fluid under pressure to said brake cylinder, means for controlling the energization of said track shoe braking means comprising a pressure operated switch responsive to brake cylinder pressure and an inertia switch responsive to the rate of retardation of the vehicle, and pressure controlled means for lowering said track shoe into engagement with the track rail upon the supply of a braking current thereto and for raising said track shoe from engagement with the track rail upon the interruption of the braking current to the track shoe.

17. In a vehicle brake system, in combination, an electric brake device, a manually operable brake controller, and inertia controlled means conditioned by operation of said brake controller to a brake applying position to establish a circuit for energizing said electric brake device and operative in response to the rate of retardation of the vehicle to maintain said circuit closed.

18. In a vehicle brake system, in combination, an electric brake device, a manually operable brake controller, and inertia controlled means conditioned by operation of said brake controller to a brake applying position to establish a circuit for energizing said electric brake device and operative in response to the rate of retardation of the vehicle to maintain said circuit closed, and. operative to open said circuit below a chosen rate of retardation.

19. In a vehicle brake system, in combination, electric brake device, a manually operable brake controller, means operable upon operation of said brake controller to any brake applying position in an application zone for establishing a circuit to said electric brake device including a fixed resistor that is designed to permit the flow of magnetizing current only therethrough, and

fluid pressure controller means for establishing a braking circuit in shunt to said resistor and to control the current therethrough in accordance with the degree or" operation of said brake controller in said application zone.

20. In a brake equipment for vehicles, in combination, a brake cylinder, magnetic track shoe braking means adapted for engagement with the track rails, manually operable means for effecting the supply of fluid under pressure to said brake cylinder and for establishing a magnetizing circuit for said track shoe, and means responsive to brake cylinder pressure for establishing a braking circuit for said track shoe, after the magnetizing circuit is established.

21. In a vehicle brake equipment, a magnetic track shoe brake device, means manually operative to cause application of the track shoe brake device, and inertia means responsive to the stopping oi the vehicle for eifecting release of the track shoe brake device independently of the manually operative means.

22. In a vehicle brake equipment, a magnetic track shoe braking means having an electromagnet, means manually operative to cause said electromagnet to be energized for a certain interval of time, and inertia means responsive to the retardation of the vehicle Within said certain interval of time for preventing deenergization of said electromagnet as long as the vehicle continues in motion and efiective when the vehicle stops to cause deenergization of the electromagnet.

BURTON S. AIKMAN. 

